Stereoscopic apparatus



March 25, 1930. w. P. Rl-:AvEs 1,751,530

sTEREoscoPIc APPARATUS y original Filed nem-ie, 1925 12 sheets-sneer 1 IVR abbozweg .l

March 25, 1930. l w P, REAvEs l 1,751,530

sTEREoscoPIC APPARATUS Or'glnal lFiled-Dec. 16. 1925 12'5heets-Sheet 2March 25, 193.0. w. P. REAvEs 1,751,530

STEREOS GOPIC APPARATUS Original Filed Deo. 16. 1925 12 Shees-Sheet 5 l"nl",

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sTEREoscoPIc APPARATUS Original Filed Dec. 16. 1925 l2 ,Sheets-Sheet 5 AS14/vento@ March 25, 1930. w` P, REAvEs 1,751,530

sTEREoscoPIc APPARATUS Original Filed Dec, 16. 1925 12 Sheets-Sheet 6March 25, 1930.

w. P. REAVES STEREOSCOPIC APPARATUS original Filed bec. 1e. 1925plllllzav nu!!! l//m n l .av u 7 .March 251930 W P- REM/Es 1,151,536

STEREOS COPIC I APPARATUS originan Filed Dec. 1e. 1925 12 sheets-sheet 8March 25, 1930. w. P. REAvEs l 1,751,530

sTEREoScoPIc APPARATUS l I Original Filed Dec. 16. 1925 12 Sheets-Sheet9y March 25, 1930. w. P. REAvEs sTEREoscoPIc APPARATUS origina1 FiledDc. 1e. 1925 A12: sheets-sheet 1o` Y aucun@ .z -EZ March 25, 1930.

w. P. REAvEs 1,751,530

.STEREOSCOPIC APPARATUS Original Filed DBC. 16, 1925 l2 Sheets-Sheet l2Patented Mar. 25, l 1930 iT-E f1.: f STATES WILLIAM P. REA'VES, 0FGREENSBORO, NORTH CAROLINA ySTEREOSCOPI() APPARATUS Application filedDecember 16, 1925, Serial No. 75,822. Renewed September 2, 1.926.

The present invention relates to stereoscopic apparatus and particularlytosteieoscopes of the Wheatstone orl reflecting type designed andconstructed yfor use in radiographic diagnosis.

This application is a continuation in part of n'iy copendingapplication, SerialNo. 672,- 572,1iled November 3, 1923. In radiographicdiagnosis, particularly Where it is desired to obtain a true estimate otthe position of a toi-eign objectvvithin the human body or to studytissue changes caused by disease, it is the present practice to take twoseparate radiographs With thetarget of the X-ray tube atpoints abouttivo and onehall' inches apart, 'which is the average interpupilarydist-ance, and to mount the paired radiographs in a stereoscope to besiinultane` ously observed by the diagnostician. r

By viewing the paired radiographs reflected from suitable mirrors withthe observers eyes positioned at points bearing the same re-v lationvtotheradiographs as the target off the XV-'ray tube bore to the cassetteor holder when the radiograph tllins were' exposed, aninipres sion ofrelieic is obtained from which the diagnosticiancan malte deductionsasto the size, depthfand position of foreign bodies in the human body,or study the changes of diseased tissues. In-takingthe radiographs thetarget is placed at any desireddistance from the plate in the cassette,usually about-twentyive inches, Which'is a distance at Which nor- Vmaleyes'easily focus. One plate iis exposed for each position of the targetor" the X-ray tube and, 'after being developed,theseplates areplaced-facing each other in 4such position thatby means of reliectingmirrors position ed intermediate the same,the Vobserver may see oneplate'wvith one eye andthe other plate Withthe other eye, theitvvopictures appearing as one in relief, the plates are properly. ar ranged.,The plates 'shouldbe arranged in the stereoscope with greatl care andexactitude in order that the objectmay be viewed Without distortion orundue fatigue upon the eyes. Taking any particular pointon oneradiograph, for instance, the light ray from this l in differentpositions upon tivo plates ot' a set, ldue to the fact that the tivoplates are not held in exactly the same position in the cassettewhen theexposures are made. Thus an obj ect which may appear in the` center ofone plate may be not only horizontally randvertically displaced from thecenter of the second plate but may also be at adiiierent angle to thesiderot the plate. 'In the old type of stereoscope invvhich the platesbore a fixedangular relation tov the mirrors, such disalignment Wouldprevent the proper portrayal of' the binocular image. scope two picturesofthe saine object may be substantially aligned, notwithstandingditterences in thepositioning'of the images on* their respective plates.That such inisalignment oftenocours in practicevvillbeseen from o thefact that in order toge't anobject .in the samey position on the tivoplates, isnecessary to Vhave the tWo plates placedin the cassette inexactly corresponding positions, and it is Y alsonecessary to move tneX-'ray tube between .the exposures, the interpupilary distance in a Inmy improved stereov f the corresponding illV the two images on theirrespective plates often occur. lllhere means not provi ed adjusting theradiographs relative to the rors, the Vioesult would be ak distortion orobject and a considerable strain upon the observers eyes.

A stereoscopic apparatus according to my invention comprises ay pair ofradiograph supports or illuminating boxes facing each other and adaptedto be moved toward or from each ot`l er in unison, since the radiopliplates must ai ways be equidistant from the mirrors. lilidway betweenthe two illuminating boxes is in it-ed a mirror box con taining twomirrors at an angle of 90o to each other and normally at an angle of 45oto i ating box. Means d lowering the enay be adjusted to u it in eitherstandg or sitting positions. Each illuminating ,Jox is pivotally mountedabout both horiZontal and vertical axes. lans are also provided for soconnecting the illuminating boxes to the mirror oox that therelationship of the observers eye to any point on the correspond* ingplate is not altered upon horizontal movenientl of the mirror box toaccommodate the apparatus to the peculiarities of vision of theobserverl or upon vertical movement of the same to inspect the tops orbott ns the plates. ln order that the relationship between the platesand the observerls eyes may not be destroyed by any such movement of themirror box, the radiograph supports are connected to the latter in suchmanner that vertical or horizontal movement of the mirror box results incompensating movement of the illuminating boxes. j ln other words, it isnot only possible toy place the several boxes in the precise relationdesired initially, but this relationship is substantially maintained forall adjustments of the mirror box. The mirror box may also be freelyrotated on a vertical axis to inspect points adjacent the front or rearedges of the plates. l

Lenses are provided in connection with the mirror box to assist infocusing the eyes upon the radiograph films, and also for the purpose ofenlarging the images. rlhese lenses are mounted in a novel manner sothat they may be swung into or out of operative position and also may beadjusted towards or from the mirror box in unison. They eliminate thenecessity of using reading glasses for Vclose study of the radiographfilms.

My apparatus also includes means for plac-V ing a color screen betweeneach of the radiosrraph plates and the source of light therefor.

.lie color of this screen may be changedto suit the necessities of anyparticular type of radiograph films, thereby increasing the stereoscopiceffect due to the binocular angles at which the two radiograph filmswere exposed, and giving greater depth, position and detail to thesingle transparent image formed by the fusion of the two radiographVIEWS.

The supporting stand and the means for mounting the reflecting andillun'iinating boxes are also of novel construction, and the apparatusas a. whole has many features of novelty not specifically pointed outabove, which will, however, be pointed out in the appended claims.

lt is ie general object of this invention to provide a stereoscopicapparatus by means of which the greatest degree of accuracy ofobservation may be realized by the observer.

is a further object of the present inven tion to provide means foradjusting the raiograph supports relative to the mirrors so nat thepositions and angles of the plates or iilins to the target of the r-raytube when the former were exposed may be substantially i 1icated.

Lt is a. still further object of my invention to provide means forsimultaneously coordinating the positions of the radiograph supports andthe mirrors so that movement of the latter results in compensatingmovementl of the former, whereby the mirrors may be moved toccoi'ninodate the same to the peculiarities of vision of the observer orin inspecting various parts of the plate without disturbing the angarrelationship of the observers eyes to the radiograph plates.

Another obj eet of the invention is to provide chromatic illumination bymeans of which the details, position and dimensions of the object underobservation are intensified, thereby increasing the efficiency ofinterpretation and diagnosis. Y

@th er objects and advantages of my invention will be apparent from thefollowing description, taken in conjunction-with the accompanyingdrawings, which form a part of this specification, and in which, l

igure l is a front elevation of the entire apparatus Figure 2 is a topplan view thereof;

Figure 3 is a vertical section taken on the line 3 3 of Figure l;

Figure l is an enlarged fragmentary view of a portion of Figure 3, partsbeing broken away;

Figure 5 is a detail view showing the manner in which the illuminatingboxes are mounted to slide on their supporting rails:

Figure 6 is an enlarged vertical section thru one of the illuminatingboxes, taken on the line 6 6 of Figure 7 Figure 7 is a fragmentaryhorizontal section taken on the line 7 7 of Figure 6;

Figure 8 is a detail view taken substantially on the line 88 of Figure6; Y

Figure 9 is a fragmentary vertical section taken on the line 9 9 ofFigure 6;

' Figure 10 is a similar view taken on the line 10-10 of Figure 6;

Figure 11 is an enlarged fragmentary horizontal section taken on theline 11-11 ofFigureG; *Y f Figure 12 is a. fragmentary vertical sectiontaken on the line 12-12 of Figure 10 showing theV construction of thestop mechanism for the color roller;

Figure 13 is an enlarged elevation of one end of one of the plateholders for the illuminating boxes and its associated parts;

Figure 14 is a plan View ofthe same7 tal-:en on the line 14-14 of Figure13;

Figure 15 is a vertical section taken on the line 15-15 of Figure 13; i

Figure 16 is a perspective View of the same; Y

Figure 17 is adetail plan View of the light casing of one of theilluminating boxes;

Figure 18 is a section on the line 18-18 of Figure 17;

Figure 19 is a detail front elevation of the wet iilm holder andassociated parts;

Figure 20 is a side elevation of the same, parts being broken away;

Figure 21 is an enlarged side elevation of the mirror box and itsassociated parts, the supporting framework being shown in section, andthe View being taken substantially on the line 21-21 of Figure 1;

Figure 22 is an enlarged vertical transverse 'central section thru aportion of Figure 21;

Figure 23 is a fragmentary horizontal section taken on the line 2323 ofFigure 22;

Figure 24 is a similar View taken on the line 24-24 of Figure l22; Y

Figure 25 is an enlarged horizontal section thru the mirror box;

Figure 26 is an enlarged fragmentary horizontal section taken 'on theline `26-26of Figure 1;

Figure 27 is an enlarged fragmentary Vertical section taken on the line27--27 of Figure 1 l k Figure 28 is a detail View showing thevconstruction of theball bearing shown in Figure'27; n

Figure 29 is a detail View taken on the line 29-29 of Figure 27; i v fFigure 30 is an enlarged front'elevation of the mechanism connecting themirror box and the illuminating boxes; parts being broken away g Figure31 is a sidekelevation of the same; Figure 32 is an enlarged centrallongitudinal section of a portion of Figure 30; showing the details ofthe universaljoint;

Figure 33 is a front elevation ofan indieatingV marker carryingidentifying matter which is radiographed on the plate or film; Figure 34is a side. elevation of the same; Figure 35 is a side elevation ofapatients head showing diagrammatically the exposure angles of a pair ofradiographic plates with the tube and the cassette in certain relativepositions. v i

Figure 36 is a diagrammatic front View of one of the 'plates exposed asin Figure 35, showing the position in which it is mounted ink one of theilluminating boxes of the stereoscope p Figure 37 is a front elevationof my marker; showing the indicating elements thereon in the correctposition for platesexposed as in Figure 35; Y

Figure 38 is an end elevation of a patients head looking from head tofoot and showing diagrammatically the exposure angles of a pair ofradiographic plates with the tube in di'erent positions with respecttothe cassette than in Figure 35;

Figure 39 is adiagrammatic front View of oneof the plates exposed as inFigure 38, showing the position in which it is mounted Y in one of theilluminating boxes of the stereoscope;

Figure 40 is a front elevation of my marker; showing the indicatingelements thereon in the correct position Vfor plates exposed as inFigure 38;

Figure 41 is aside elevation of a patients head showing diagrammaticallythe exposure angles of a pair of radiographic plates with the tube linstill different positions with respect tothe cassette;

Figure 42 is an end elevationof the same, looking from head to foot;

Figure 413 is a diagrammatic front View of one of the plates exposed asin Figures 41 and 42; showing the positionin Vwhich it is mounted in oneof thevilluminating boxes ofV the stereoscope; v 'Y Figure 44 isa frontelevation of my mark'- er; showing the indicating elements thereon inthe correct position for plates exposed asy in Figures41 and 42;

Figure 45k is ak side elevation `of a patientsV head showingdiagrammatically the Vexposure angles of a pairV ofradiographicplateswith tlievtube in still other positions with respect to the cassette; Y

Figure 46 isa diagrammaticfront -yiew of one of the plates exposed askinyFigure 45V showing the position in .which it is mounted` in one oftheilluminatingboxes of the stereo- Figure 47 is a Vfront elevation ofmy marker, showing the indicating elementsthereon in the correctposition for plates exposed as in Figure 45; 1 v

Figure 48 is an end elevation of a patients body lookin@- from foot vtohead, showing diagrainmatically the exposure angles of a pairofradiographic plates in still other positions of the tube with respectto the cassette; i

Figure 49 is a diagrammatic front View of oneof the platesexposed asinFigure 48, Y

t reference showing' the position in which it is mounted in one of theilluminating boxes of the stereoscope;

Figure is a front elevation of my marker, showing the indicatingelements thereon in the correct posit-ion for plates exposed as inFigure 48 Figure 51 is an end elevation of a patients body looking fromfoot to head, showing diagrammatically the exposure angles of a pair ofradiographic plates in still other positions of the tube with respect tothe cassette;

Figure 52 is a side elevation of the same.;

Figure 53 is a diagrammatic front view of one of t ie plates exposed asin Figures 51 and 52, showing the position in which it is mounted in oneof the illuminating boxes of the stereoscope g Figure 54 is a frontelevation of my marker, showing the indicating elements thereon in thecorrect position for plates exposed as in Figures 5l and 52;

Figure 55 is a diagram showing how the mirror box may be movedhorizontally to compensate for peculiarities of the observers visionwithout disturbing the angle which the light ray from a given point onthe plate to the observers eye makes with the plate;

ligure 56 is a diagram showing how the mirror box may be movedvertically to bring a point near the top or bottom of the plate into thedirect line of the observers vision without disturbing the angle which tie light ray from that point to the observers eye makes with the plate;

Figure 57 is a diagram showing how the mirror box may be rot-ated aboutits vertical axis to inspect a point near ythe front or rear edge of theplate; and

Figure 58 is a diagram showing the effect upon the positionsl of theilluminating boxes of a simple rotative movement of the connectingmechanism.

Referring to the drawings, in which like characters denote like partsthroughout the several views thereof, and more particularly to Figures1, 2 and 3, a pair of end supports 50, each of which is preferablybifur'cated as shown in Figure 3, are rigidly'joined by a channel-shapedcross bar 51 securely bolted thereto. Guides 52 are secured at each endof the bar 51 and areprovided with lugs 53 adapted to hold in placesquare supporting rods 54. rllhe upper ends of these supporting rods 54are bolted to trapezoidal shaped webs or frames 55, each having its topand bottom edges horizontal and its back edge vertical, to theV bottomof which are secured a pair of horizontal beams 56 which correspondtothe usual table for supporting the various parts of therapparatus. Tothe upper end of each web 55 is secured a pair of channel-shaped rails58, the grooves of which face towards each other. rlhe rails 58 and thebeams 56 are connected together at their outer ends by trapezoidalshaped frames or webs 59, which may be somewhat similar in constructionto the webs 55, except that the center brace of the latter isunnecessary here. The beams 56 extend the entire length of theapparatus, whereas the rails 58 only extend outwardly from the webs 55,each pair of rails forming a trackway one of the illuminating boxes. Thefront beam 56 is shown-as a channel bar, while the rear beam 56 is shownas an angle bar, but this particular point is immaterial, and anydesired construction may be adopted.

'The lower end of each of the supporting rods 54 has secured thereto acable 61 passing around a pulley 62 mounted on a shaft 63 secured tocross bar 51, and secured at its lower end to a counterweight 64'whichis designed to counterbalance the weight of the entire apparatus, sothat the rods 54 may be readily moved up or down in their guideways andwill remain in any position in which they are placed.

A vertical panel 65 is secured at its ends to the back vertical edges ofthe webs 55, and serves to support various parts of the apparatus, aswill be pointed out hereafter.

illuminating boxes are mounted to slide upon each pair of rails 58, andare arranged so as to face each other. The iluminating boxes areidentical in construction and one only, therefore, need be described.Each illuminating box comprises a base or platform 101, shown clearly inFigures 2 and 4, which is provided with wheels 102 adapted t0 roll inthe grooves in the channel-shaped rails 58. AThe rails 58 are preferablyprovided with shoulders 103 which bear against the ends of the wheels102 so that the platforms 101 are accurately centered, at the same timewith less resistance to the movement of the wheels than would be thecase if the entire inside face of rails 58 bore against the ends of thewheels 102. The platform 101 is provided at its center with a hub orboss 104 thru which extends a spindle 105 carrying at its upper end ayoke 106. This yoke may be made in one piece or of three pieces joinedtogether as shown in Figure 4. The illuminating box 100 is pivoted abouta horizontal axis between the arms of the yoke 106. The illuminating boxmay thus be given a rotative movement about the axis of spindle 105 or atilting movement about the horizontal axis thru yoke 106, or both, asmay be desired.

Means is provided as illustrated in Figure 2 for moving the illuminatingboxes 100 t0- ward or from each other in unison on their rails 58. A.horizontal shaft is mounted in a suitable bearing in panel 65, and has ahand wheel 111 on its front end and a pulley 112 on its back end.Pulleys 113 are mounted on each of the upper rear corners of the framework so as to rotate on a vertical axis. A lug or hook 114 is secured toeach of the platlug, and is then secured to the irst lug 114.

By this construction, rotation of the lhand wheel 111 willcause theilluminating bones to move towards or from eachother in unison.

The construction of `the illuminating boX proper is shown in Figures 6to 18. Each boX comprises a rectangular frame which may be constructedofwooden bars. v A metal frame 151 extends completely around the woodenframe and is set into a groove in the outer surface of the wooden frameas shown in Figure 7. rlh'e frame 151 is provided with an integralforwardly Vextending flange 152. Angley bars 153 are secured-to theouter ends of the frame 151 so that the free end of the angle barprojects in front of, butiis slightly spaced from the flange 152. Eitherthe .wooden frame 150 or themetal frame A151 may be constructed infpartssok that they may be joined together by thetongue and grooveconstruction as shown in Figure 7 and-described above. A Amember 154 issecured to the frame 151 an'd angle bars 153 at the center of each` sideof the illuminating box, and is provided with aspindle 155 which isjournaled in an aperture in the upper end of yoke 106. A nut 156 isthreaded on the end ofeach Aspindle 155,7and prevents the spin'dlesrfromcoming out of the yoke. The shape of the-members 154 is best shownin-Figures 6 and 11.

,A pyramid-shaped sheetmetal light casing 157 is secured to the back ofthe frame 150, `as y shown in Figures 7 and 9. yThe casing is jpreferably made in'two pieces joined on a ver-' tical plane. Each halfis provided along its top and bottom edges with .projecting finsV 158.The front portionsof these-fins areL clamped closelytogether by rivets159, but the rear portions are spaced apart by spacing washers 16() onrivets 161 as shown in Figures 17 and 18. Upper and lower Ventilatingopenings are vthus provided which serveto keep the light bulb and theilluminatingl boX v cool. The small end .of thecasing 157 is closed by avertical plate 162.. which carries a socket 163 supporting an electriclamp 164, both -shown diagrammatically in Figure 18.

A glass plate 165 is set inthe front of `the frame 150 as shown inFigure Each illuminating boX is provided with two vertical and twohorizontal curtains so arranged that a film or plate may be supported inthe Jcenter of the illuminating box in front ofthe glass plate 165. Asquare block 16.6 is secured tothe frame151`near each corner thereof.

`rThese blocks serve as bearing blocks for the curtain rollers, whichmay be-spring rollers of any usual type. The horizontal rollers 167haveA shafts `extending completely thru the blocks 166, as showninFigure 6. |l`he shafts into the blocks 166 to securely support thesame, but not far enough to interfere with the shafts of thehorizontalrollers 167.

Each of the vertical rollers 168 is provided with an opaque curtain 169.One end of the curtain is secured to the roller and the other end isprovided with a U-shape'd piece of Isheet metal r fastened thereto asshown in Figures 6 and 7. Each of'these metal strips 4is provided with ahandle 171 which may be formed of a stiif wire loop. The curtains 169are guided in a vertical plane between the "edge of frame 150 and ofangle bars 153. The Vends of the metal strips 170 are each connected tova chainv172, which passes over 'sprockets 173 secured to the shaftsofthe rollers 168.

The ends of the chains 17 2 are connected together bycrossed wire cables17 4 as shown in Figure 8. Itwill be seenthat if the operator grasps oneof the handles 171 and moves the .corresponding-curtain 169 in eitherdirection ,the other curtain 'of the vertical pair willbe moved in theopposite direction, so that'the two curtainsare moved towards or lfromeach other in unison this construction, and the opening lbetween them isalways accurately centered'with respectto the illuminatingbox asawhole.j

The horizontal rollers 167,'are similarly provided with opaque vcurtains17,5. These curtains are preferably mounted infront of 'thecurtainsl169.` The free end of eachcurtain 17 is clamped betweenasquaiebar 176 and a bent sheet metal member 177, theconstructionof-which is most clearlyl shown in of the vertical rollers168 project far enough Figure16. Each endof the bars 176 is sey l curedVto anear 17 8 projecting outwardly from a plate-like member 179. VThemembers "179 are adaptedto slide in the space between Vthe flange :152and the angle bar-.153, which serveto guide them in avertical plane. An

arm orflink`186 is'pivoted to the'ear 178 and i at` vitsgouter, endcarries a rotatably'mounted shaft 181 provided with a hand wheel 182.A'pinion 183 is fixedly secured to'said shaft 181 and is adapted toengage a iiXedpinionv 184'secured to the'ear 178. ltvvill thus be seenthat byturning the hand wheelf182 the 'pinion 183 will rotate about thepinion 184 thereby producing a corresponding .rotation of the link 180,the pivotal aXis lofthe link l being-'onthe same line with the center ofvthe pinion'184. Theshaft 181 is provided with a pluralityfofsoft rubberrollers l185 secured thereto,*these vrollers being adapted to engage aflange 186vwhich forms an inte. gral part of the sheet metal member 177.A `vwire spring187 hasone'end'heldn ar slot 188 y im. l.

formed in the member 179, andthe spring wire is bent so as to bear upona grooved portion of the shaft 181 and a grooved extension tively.

The means for operating the horizontal curtains is shown in Figures 10and 11 and will now be described. A slotted plate 190 Vis mounted so asto slide vertically against the flange 152 of the frame 151. The slot isprovided with internal rack teeth 191 on one side thereof and 192 on theother side thereof, these sets of teeth beingv laterally spaced fromeach other as shown in Figure 11. A shaft 193 carrying a hand wheel 1911passes horizontally thru an aperture in the spindle 155 and has itsinner end mounted in a bearing in flange 152. A pinion 195 is secured tothe shaft 198 and is of such width as to engage with the rack teeth 191or the rack teeth 192, but not both at the same time. The shaft 193 ishorizontally movable in its bearings so that the pinion 195 may beplaced in position to engage the desired set of rack teeth. A sprocketwheel 196 is also secured to the shaft 198 and is connected to asprocket 197 on the shaft of the upper curtain roller 167 by a chain198. A sprocket wheel 199 is rotatably mounted on a stud shaft 200secured to the fiange 152, andy is connected to a sprocket wheel 201onthe shaft of the lower roller 167 by a chain 202. The lower curtain issecured to the sliding rack 190 and the upper curtain is secured to thechain 198.

When the hand wheel 194 is in the position shown in Figure 11 and isturned in a counterclockwise direction, looking lat Figure 10, the rack190 will be moved upwardly carrying with it the lower vertical curtain.At the same time the upper vertical curtain, which is secured to thechain 198, will be moved upward an equal distance so that the spacebetween the two curtains will remain thev same. lf now the hand wheel194 be pushed inwardly so that the pinion 195 engages'the rack teeth191, the rack 190 will be moved downwardly if the hand wheel is rotatedcounter4 clockwise, ywhile the upper vertical curtain will continue tomove upward, thereby increasingthe distance between the curtains. Byreversing the direction of rotation of the hand wheel 194 the curtainsmay be brought closer together. The method of procedure is to firstsecure the correct distance between y the curtains, mountthe radiographbetween the rollers 185 and flanges 186, and then move the curtains,maintaining the same distance between them, until the radiograph isaccurately centered.

Means are also provided for inserting a colored screen between thesource of light and the radiograph. rllhis preferably takes the form ofa pair of horizontal rollers 219 having shafts 211 mounted in ears 212secured to the frame 151, as shown in Figure 9. A sheet metal casing 213surrounds each of the rollers 210. A color roll 214 is mounted on therollers 210 and passes thru openings 215 in the light casing 157.Sprocket wheels 216 are secured to the shafts 211 of each of the rollers210 and are connected by a chain 217. The color roll may be moved intothe desired position simply by pulling on one side or thc other of thechain V217 which is disposed on the outside of the illuminating boX.Different sections of the color roll may be made in different colors sothat light of any desired color may be secured simply by bringing thedesired portion of the color roll into operative position. One sectionof the roll is made of colorless, transparent material so that theelectric light may be used in its natural state if desired.

One ofthe rollers 210 is preferably provided with an automatic stop suchas is shown in Figure 12, which is designed to prevent the chain 217from being pulled too far so that the color roll would be torn loosefrom the rollers. For this purpose, one end of one of the shafts 211 isthreaded with threads of a suitable pitch, and is provided with atraveling nut 218. The nut 218 is prevented` from rotating with thethreaded shaft 211'by a rod 219 secured at one end in the ear 212 and atthe other end in a member 220 mounted within the casing 213 adj acentthe end of the roller 210. By properly proportioning the distancebetween the ear 212 and the member 220, and the pitch of the threads Vonshaft 211, the nut 218 will come in Contact with one stop or the otherjust as the color roll is' completely unwound from the roller, and thusprevent the color roll from Vbeing torn loose.

' As shown in Figures 1 and 21, a square mirror box supporting rod 250passes thru a grooved bearing member 251 secured to the center of thefront of the cross bar 51. The upper end of rod 250 is secured to atransverse horizontal member 252 which is also supported by a secondvertical rod 253, preferably square in cross section, which passesdownwardly thru another grooved bearing member 254, fastened to the rearof cross bar 5,1. A circular rod 255 is secured to supports 256 mountedon each end of the horizontal member 252 and forms a trackway for asliding rectangular block 257. As is clearly shown in Figure 27, thelower end of vertical rod 250 is connected to one end of a spiralspring` 258, the other end of which is secured to a stud 259 mounted onthe front of cross cal panel 65.

bar 51, the entire spring being housed in a recess in bearing member251. The spring 258 will be wound up when the rod 250-is lowered andunwound when it is raised, thereby partly counter-balancing the weightof the mirror box and making it easier to raise the same.

Means is provided for locking the vertical rods 250 and 253 inl thedesired position of vertical adjustment. The meansl for vrthis purposeis clearly shown in Figure 26, and comprises a lever 260 pivoted at 261to the cross bar 51 and provided with a handle 262. The ends of thelever 260 are cam-shaped and are adapted to engage'the inner faces ofthe rods 250 and 253 and jam the same in the recesses which they slide.

A cylindrical stud 263 having a reduced portion 264 is secured to thesliding block 257 and fits into a recess in the lower end of a circularrod 265. rEhe rod`265 is provided with a slot in its side thru whichextends a bifurcated piece 266, shown clearly in Figures 27 and 29,which engages the reduced portion 264 of stud 263. This constructionsecurely locks the rod 265 against vertical movement relative to thestud 263, but permits rotation thereof. e

rEhe sliding block 257 is. provided with a ball bearing 267mountedtherein. The construction of this ball bearing 267 ispreferably-as shown in Figure 28. VA hollow cylinf der 268, the'insid-ediameter of which is slightly greater than the outside diameter of rod255, is cut thru in two places along lines at an angle. of 45o to itsaxis, thereby dividf ing it into three pieces. One end piecev is placedin a cylindrical aperture in block 257 and secured thereto by Ysuitableset screws, a row of balls inserted, the middle piece putin next,another row of balls inserted, and the other end piece then put in placeand similarly secured to the block 257. vThe block 257 must, of course7vbe mounted on the rod 255 at the time the bearing is assembled, asotherwise the balls would fallout. It has been found that'the bloc-k 257slides more readily when a bearing of this construction having diagonalrows of balls is employed.

ylhe rod 265 vpasses upwardly 'thru ahub 275 having an integralrectangular flange 276 extending therefrom. The ange 27 61s providedwithstrengthening webs 277 onV thel under side thereof and is mountedfor transverse sliding m ovelnent on' a pair of-rails 278 fitting ingrooves along its sides; The rails 278 are secured attheirrear ends tothe verti- The front ends of the rails 278 are connected .together by across piece 279 and to the forward beam 56 by vertical mem# bers 280. fi l y The rod 265 is `provided along one` side thereof with a pluralityofr rack teeth 281, these teeth being disposed adjacent thehub 275. TheVhub 275: is provided withv a. collar 282 extending therethrough betweenit and' the rod 265, as shown inV Figure 22. The upper end of thiscollar isprovided with a shouidery 283 which rests upon the top of thehub 27.5. The collar 282 is providedy with a pair laterally extendingears'284 `positioned on either side of the rack teeth 281, and a. pinion285 is mounted between these ears on a shaft 286 in position to engagethe rack. The shaft 286 is 'provided' with a hand wheel 287.*fo'rrotating the same. A washer 288 is secured to the lower end of thevcollar 282 in position to engage thevlower end of the hub 275, and isadapted, in cooperation with the shoulder 283,v to prevent verticalmovement of the collar 282 relative to the hub. The washer2-88 is cutaway along a portion of its circuinference to form a sector-shapedrecess 289 (Figure 23) ,the sides of which are adapted to en.-

gage al pin 290 set in the hub 275. This construction permits the' rod265 and the collar y 282 to rotate as a unit relative to the hub 275thru the angle subtended by the sector 289. This rotation may be'secured by means of the shaft 286 and hand wheel 287. y

The'upper end oftherod 265 above the rack teeth281 is reducedindiameter, formingv a shoulder 300, `on which rests an arm f 301, therod 265 passing thru an aperture in the arm' 301 and being freelyrotatable relative'thelreto. e The arm 301 is provi-ded with adownwardly extending apertured boss 302 thru which extends a verticalrod 303 which is screwedinto va boss 304 on the fiange v276. r'hevertical rod 303 serves to preventthe leo arm 301 from rotating withtherod 265, and Y acts also as a brace. VThe rod-303 extendsaVshortdistance up into the mirrorbox 'thru an arcuate slot in the bottomthereof, and the boss 302 is prolonged downwardly,"inv order that therody303 may continue' to engage the arm 301 when the rod 265 is in itsuppermost posit-ion. rlhe rod 303 'must be short enough so that'it willnot strike the top of the mirror box. when the rod 265. is kin itslowest position with the arm 301y engaging the collar l282.

' Similarly, the boss 302 must not extend down so far aste strike theboss 304 beforethe arm 301 touches the 'collar 282.

i member 305is securedto the 'upperend of rod 265 and has securedthereto a recessed member 306 on vwhichis mounteda mirror 'box 307. Themirror box may be of the Vtype disclosed in my Patent No. 1,487,47 3,issued March 18, 1924, and comprisesa bottom 308 anda top 309 connectedtogether at the Vrear` corners by angle hars 310, and at thefrontcornersk by vertical frame members 311'.- As shown in Figure 25,two mirrors 312 are mounted within the box at an angle of 90o los y wieto each other and each making lan angle ofy 45 withv the frontfof thebox, and are secured to right angledv support-s 313 fastened to thetop-k 309 andlbottoni308, respectively. The mirrors are preferablysilvered oli-'their front surfaces and are completely protected baclr bythe action of the gears 328.

from dust and moisture by glass side wall. 314, glass front walls 315,and a nose piece 316. A pair of side doors 317 and a pair of front doors318 are provided and are pivoted [on vertical axes to ears secured tothe front corners of the box.

These doors are preferably geared together, as shown in my patent, sothat they are opened or closed imizltaneously, and serve to protect theglass side and front panels from dust as well as acting as shields forthe observers eyes when the instrument is being used.

Lenses 325 are secured to bleclrs 326 which are slidably mounted on arms327 at either side of the mirror bof; 307. rl`he inner ends of the arms327 are secured to gears 32 pivoted on studs 329 secured to me. .eer 30the gears 328 being mounted in recess in nember 306, as shown in Figures22 a -l 2e. When the apparatus is not in use, the lenses may be movedinto proximity with the glass side walls 314 of the mirror box, and beprotected behind the side doors 317, as shown in dotted lines in Figure25. if? hen it is net desired to use the lenses, they may be pus ledback out of the way by pushing on one of the arms 327, the other armbeing likewise moved Pulleys 327 are mounted on the ends of the arms327, and are connected with each other and with the sliding blocks 326on which the lenses 325 are mounted, by means of cord 330, in much thesame manner as the illuminating boxes are connected together. Thussliding one of the blocks 326 along its arm, the lenses may be movedtogether or apart in unison in order to properly focus the radiographs.The cord 330 preferably passes thru apertures in the member 305. rlhisconstruction of the supports for the lenses 325 is covered in mycopending application Serial No. 659,983, iiled August 29, 1923.

As shown in Figure 22,v a vertical rod 350 extends thru the mirror boxand is secured at its lower end to the member 306 and is held in placeat its upper end by a nut 351 which clamps the rod securely tothe mirrorbox. The rod 350 has a reduced end extending thru a transversehorizontal bar-352 which is rotatably mounted thereon and held in placeby means of a nut 353. A T-shaped standard 354 is secured to the frontend of the bar 352. A tubular member 355 having ears 356 projecting fromeach side thereof is secured to the rear end of the bar 352, the head ofthe T-shaped standard 354 and the ears `356 being in the same horizontalplane. Circular rods or rails 357 are secured between the ears 356 andthe standard 354. A circular rod 358 has a reduced end passing thru theaperture in the tubular member 355 and is provided with a nut 359 on theupper end thereof. The lower reduced end of the rod 358 passes thru anaperture in the outer end of arm 301 and is secured thereto by a nut Therod 358 thus serves to hold the bar i and its rails 357 from rotatingwith the mirror box.

A member 361 is provided with arms extending from each side thereof,each of which carries a sleeve at its cuter end. The member 361 isarranged to slide on the rails 357, which pass thru the apertures in thesleeves 363. @ne of the sleeves 363 is provided with a lnurled set screw364, which serves to loclr the member 361 in any desired position on therails 357.

A square rod has a cylindrical portion 366 which is rotatably mounted ina vertical central aperture in the member 361. A nut 367 is threadedonto the lower end of the rod 365, and keeps the same from being pulledout of the member 361. The nut 867 also serves to adjust the tension ofa curved spring 368, which bears on the rod and the arms 362 andregulates the ease with which rod may be rotated in its bearing. yEheupper end of member 361 is threaded and is provi-decl with a lrnurledloclmut 369, which has a shoulder 370 adapted to bear en a iiange 371 onthe rod 365. By means of this construction, the rod 365 may be locked inany desired rotative position.

TLiefer-ring particularly to Figures 21, 30 and 31, a collar 375 havingarms 376 extending laterally therefrom is adapted to slide vertically onthe square rod 365. A set screw 377 is threaded into a boss on thecollar and bears on a spring 378, thereby serving both to regulate theforce required to move the collar along the rod and to lock the collarin any desired position. The arms 376 are preferably square and areprovided with square sleeves 379 adapted to slide therealong. Set screws380 are provided to lock the sleeves 379 in place. Each sleeve 379 has adepending offsetportion, 381, in which is rotatably mounted a verticalmember 382, held in place by screw 383 and washer 384i. rlhe lower endof member 382 is fiat and is provided with a vertical slot 385. A rod386 has a reduced end which tits in slot 385 and is held in placetherein by a horizontal pivot pin 387. A dial 388 is secured to eachmember 382, and a pointer 389 secured to a washer mounted on rod 386moves over the face of the dial in accordance with the movements of rod386 about its horizontal axis. rEhe pointer 389 is so arranged thatangles which the rod 386 makes with the horizontal are changed intoangles with the vert-ical on the dial, and the dial is preferablygraduated to show angles up to 30CJ on either side of the vertical axis.The function and manner of use of the dial will be pointed out later. Itwill be seen that the vertically pivoted member 382 and the horizontallypivoted rod 386 together form a universal joint.

As shown in Figures 1 and 2, a tube 00 is

